[chrismorgan]

On the contrary, this feature has existed for decades. It’s called user-selectable alternative stylesheets: https://developer.mozilla.org/en-US/docs/Web/CSS/Alternative.... But because no one used it, the feature has not been better positioned in more recent browser UI redesigns, so it’s close to inaccessible in most browsers now. No idea if Chrome and related browsers expose it at all, or even if they’ve ripped the functionality out altogether somewhere along the way.